In continuous strip treating lines, such as continuous strip tinplating lines, it is customary to run the line continuously because of the difficulties encountered in stopping the strip, which stoppage would result in considerable length of strip remaining stationary in contact with the electroplating solution. There is thus required provision of means for holding a second coil of strip in readiness to go through the line while the first coil is uncoiling plus means for storing a sufficient length of strip so that strip can be paid out of the storage and through the plating line while the leading end of the new coil is welded to the trailing end of the strip going through the line.
One of the difficulties plaguing this type of operation has been caused by the failure to align the trailing end of the running strip with the leading end portion of the strip from the new coil. Where such alignment is not present, a misalignment, called a dog leg, occurs between the trailing end of the running strip and the leading end of the new strip. This misalignment or dog let causes considerable difficulties in the strip handling and treating operations in the processing line.
Elimination of dog leg has previously been proposed where the trailing end of the running strip is displaced laterally from the center line of the plating equipment with provisions for lateral movement of the leading end portion of the new strip so as to bring the two strip ends into lateral and longitudinal alignment at the time of the rolling operation. This development failed to take into account the fact that the trailing end of the running strip is sometimes disposed at an angle to the centerline of the electroplating line equipment.
Where it has been recognized that the running strip trailing end portion may be at an angle to the center line of the electroplating line equipment in the past, the proposed remedy has been to move the running strip trailing end portion after it has been stopped for the welding operation to bring the running strip trailing end portion into parallelism or alignment with the center line of the electroplating line equipment. In the latter development, the new strip leading end portion was also placed in parallelism or alignment with the longitudinal center line of the electroplating line equipment. After these operations, completion of the welding operation resulted in a strip without dog leg. Thus where the presence of angular displacement of the running strip has been recognized, the solution has involved complicated procedures and apparatus.
Examples of prior art systems for aligning strip end portions in continuous strip treating lines are U.S. Pat. Nos. 3,355,079, 3,370,771 and 3,577,627 and to avoid needless disclosure of specific strip handling equipment in this patent application, the disclosures of these patents are incorporated in this application by reference.
The present invention takes into account the possibility of the running strip being sometimes disposed at an angle to the longitudinal center line of the electroplating line equipment and by the simplest possible procedure and apparatus aligns the trailing end of the running strip with the leading end of the new strip to eliminate dog leg and lateral misalignment.